1. Field of the Invention
The present invention relates generally to a door window regulator for an automotive vehicle, and particularly to a wire-type door window regulator applicable to a vehicle door wherein a window pane guiding arrangement of the door window regulator is improved.
2. Description of the Prior Art
A conventional door window regulator for an automotive vehicle comprises: (a) a wire stretched along a line which lies in the plane of a window pane of a vehicle door having a predetermined radius of curvature parallel to the axis of movement thereof; (b) a guide rail attached to, e.g., a door inner panel so as to extend parallel to the axis of movement of the window pane; (c) a bracket to one surface of which the lower edge of the window pane is fixed and to the other surface of which the wire is fixed and the guide rail is engaged so as to allow the bracket to slidably move upward and downward therealong; (d) two pulleys provided at upper and lower ends of the guide rail, respectively; and (e) a drum located to one side of the guide rail around which the wire extending around both pulleys is wound so that the wire is wound around the drum or reeled in and out by the drum is rotated by means of an attached crank or an electric motor.
In the construction as described hereinabove, for example, when the drum is rotated counterclockwise and the wire is retracted into the drum from the upper pulley, the bracket is accordingly moved upward along the guide rail so that the door window pane is raised. On the other hand, when the drum is rotated clockwise and the wire is retracted into the drum from the lower pulley, the bracket is accordingly moved downward along the guide rail so that the door window pane is lowered.
The conventional window regulator usually uses a guide rail made of an elongated steel plate material having a substantially U-shaped cross section. The U-shaped guide rail is formed by bending the longitudinal edges of the steel strip material at substantially right angles to the rest of the strip. The sides of the U-shaped guide rail constitute longitudinal legs, each being perpendicular to the plane of the window pane. The edge of one longitudinal leg is bent at a substantially right angle to form a flange parallel to the plane of the window pane.
On the other hand, the bracket has a first channel portion at one end thereof into which one of the longitudinal legs of the guide rail is inserted and has a second channel portion at the other end thereof into which the flange of the guide rail is inserted. When the longitudinal leg of the guide rail is inserted into the first channel portion, the vertical displacement of the window pane with respect to the guide rail and the rotational freedom of the window pane about the bracket are restricted. When the flange of the guide rail is inserted slidably into the second channel portion of the bracket via an elastic material such as a leaf spring, the displacement of the window pane with respect to the plane of the window pane itself is also restricted.
However, there are many drawbacks in the conventional door window regulator as described hereinabove.
For example, if a piece of hot-rolled steel plate 2 mm thick is used for the material of the guide rail, the error in thickness of the longitudinal leg and flange portion of the guide rail will be 0.4 millimeters (2 mm.times.(20/100)) since the tolerance in the thickness of such a piece of hot-rolled steel plate is 20 percent. On the other hand, if a piece of cold-worked polished steel plate 2 mm thick is used for the material of the guide rail plate, the error in thickness thereof will be 0.28 mm (2 mm.times.(14/100)=0.28 mm) since the tolerance in the thickness of such a relatively high precise piece of coldworked polished steel plate is 14 percent.
Therefore, although the error between the dimensions of the flange of the guide rail and second channel portion can be cancelled by means of the elastic material described above, there will be variations in clearance between the inner and outer surfaces of the longitudinal legs of the guide rail and corresponding surface of the first channel portion of the bracket. Consequently, rotational displacement of the window pane about the bracket may occur so the upward and downward motion of the window pane will not be reliably smooth.
In addition, since some burrs will be produced at the upper edge of the longitudinals leg during processing of the guide rail, and contact with such burrs may damage the second channel portion of the bracket, a separate operation for eliminating such burrs is additionally necessary.